Alan Stern Visits Flagstaff to Discuss Mission to Pluto

Jun 6, 2018

In the last few years, Pluto has gone from being a fuzzy dot in the sky to a geologically active world of mountains, canyons, and heart-shaped glaciers. That’s thanks to NASA’s New Horizons spacecraft, which sailed by Pluto in 2015 to photograph it up close for the first time. The mission’s leader Alan Stern is currently on a book tour and visits Flagstaff today. He spoke with KNAU’s Melissa Sevigny from the road.

Pluto, photographed by New Horizons
Credit NASA/JHUAPL/SWRI


Hi, Alan, thanks for joining me.

Great to be here.

In the last few years scientists have learned so much about Pluto, thanks to all the data coming back from New Horizons. What has surprised you the most?

One is that we did not expect Pluto to have the level of geological and atmosphere complexity that it does. We’re calling it the new Mars. It’s as complicated as Mars or even the Earth…. But also Pluto is   amazingly geologically active which was also not expected, because it’s a small planet and it was thought it had cooled off and its geological engine had died. So we were surprised to find terrains on the surface, enormous expanses, even the size of Texas, that are born yesterday geologically… We have strong evidence Pluto has an internal ocean of water, we see glaciers on the surface that span a million square kilometers… We also see evidence for avalanches, and even for volcanoes on the surface, ice volcanoes called cyro-volcanoes.

That’s really neat, yeah. Here in Flagstaff astronauts used to come here to train for missions to the Moon. Is there a landscape here on Earth that would be the perfect training ground for Pluto?

That’s a really good question, because Pluto’s surface is covered in ices almost everywhere. …. The dominant ice on Pluto’s surface is actually condensed molecular nitrogen, which is a gas in our atmosphere, but which is a snow on Pluto’s surface. Probably the best analog terrains are in the Arctic and Antarctic in terms of ices, and icy geology. 

So snow made out of nitrogen, what does that look like?

It actually looks a lot like water snow, we can make it in the laboratory, it’s bright and white, and if you looked from a distance you might think it was water snow….. There also are other ices on Pluto, including water ice, methane ice, natural gas, even carbon monoxide ice.

You’re coming to Flagstaff and that’s the home of Pluto where Pluto was discovered. You’ve probably been up to Lowell Observatory and seen that donation box up there where people can vote with their money on whether Pluto should be called a planet or dwarf planet….

I sure have. I notice the vote is always overwhelming for Pluto.

Yes, it always is. What’s your opinion about that?

I think that’s just great. You know, most planetary scientists, not just in Flagstaff but everywhere, think the astronomer’s definition of planet is nonsensical and we ignore it. Most planetary scientists that I run into consider Pluto a planet, just like people in Flagstaff do.  

Tell me a little bit about New Horizons’ next target.

We nicknamed it Ultima Thule, which is a Norse phrase for “beyond the farthest frontier.” Which is literally what it is. It’s a place unlike any a spacecraft has visited. But New Horizons is going to go very close to it, three times closer than we went to Pluto, when we do our flyby on January first.

Alan Stern, it was great to talk to you today.

Great talking to you too.

Alan Stern is principal investigator of NASA’s New Horizons mission and author of the new book Chasing New Horizons. He’ll be speaking tonight at Bright Side Bookshop at 7pm, along with local Pluto experts Kevin Schindler and Will Grundy.